<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(item,index) in arr" :key="index">
      <span>{{item["name"]}}</span>
      <button @click="buy(index)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
       
      <tr v-for="(item,index) in arr" :key="index">
        <th>{{index+1}}</th>
        <th>{{item.name}}</th>
        <th>{{item.price}}</th>
        <th>{{item.count}}</th>
        <th>{{item['price']*item['count']}}</th>
      </tr>
    </table>
    <p>总价格为:{{allPrice}} </p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods:{
    buy(index) {
      this.arr[index]['count']++
    },
  },
  computed:{
    allPrice(){
      return this.arr.reduce((sum,obj) =>{
        return (sum + obj['price']*obj['count'])
      },0)
    }
  }
};
</script>